rsa_gen.c revision 296341 
1/* crypto/rsa/rsa_gen.c */
2/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
8 *
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to.  The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 *
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the copyright
27 *    notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 *    notice, this list of conditions and the following disclaimer in the
30 *    documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 *    must display the following acknowledgement:
33 *    "This product includes cryptographic software written by
34 *     Eric Young (eay@cryptsoft.com)"
35 *    The word 'cryptographic' can be left out if the rouines from the library
36 *    being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 *    the apps directory (application code) you must include an acknowledgement:
39 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 *
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51 * SUCH DAMAGE.
52 *
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed.  i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
57 */
58
59/*
60 * NB: these functions have been "upgraded", the deprecated versions (which
61 * are compatibility wrappers using these functions) are in rsa_depr.c. -
62 * Geoff
63 */
64
65#include <stdio.h>
66#include <time.h>
67#include "cryptlib.h"
68#include <openssl/bn.h>
69#include <openssl/rsa.h>
70#ifdef OPENSSL_FIPS
71# include <openssl/fips.h>
72#endif
73
74static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
75                              BN_GENCB *cb);
76
77/*
78 * NB: this wrapper would normally be placed in rsa_lib.c and the static
79 * implementation would probably be in rsa_eay.c. Nonetheless, is kept here
80 * so that we don't introduce a new linker dependency. Eg. any application
81 * that wasn't previously linking object code related to key-generation won't
82 * have to now just because key-generation is part of RSA_METHOD.
83 */
84int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
85{
86#ifdef OPENSSL_FIPS
87    if (FIPS_mode() && !(rsa->meth->flags & RSA_FLAG_FIPS_METHOD)
88        && !(rsa->flags & RSA_FLAG_NON_FIPS_ALLOW)) {
89        RSAerr(RSA_F_RSA_GENERATE_KEY_EX, RSA_R_NON_FIPS_RSA_METHOD);
90        return 0;
91    }
92#endif
93    if (rsa->meth->rsa_keygen)
94        return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
95#ifdef OPENSSL_FIPS
96    if (FIPS_mode())
97        return FIPS_rsa_generate_key_ex(rsa, bits, e_value, cb);
98#endif
99    return rsa_builtin_keygen(rsa, bits, e_value, cb);
100}
101
102static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
103                              BN_GENCB *cb)
104{
105    BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
106    BIGNUM local_r0, local_d, local_p;
107    BIGNUM *pr0, *d, *p;
108    int bitsp, bitsq, ok = -1, n = 0;
109    BN_CTX *ctx = NULL;
110
111    ctx = BN_CTX_new();
112    if (ctx == NULL)
113        goto err;
114    BN_CTX_start(ctx);
115    r0 = BN_CTX_get(ctx);
116    r1 = BN_CTX_get(ctx);
117    r2 = BN_CTX_get(ctx);
118    r3 = BN_CTX_get(ctx);
119    if (r3 == NULL)
120        goto err;
121
122    bitsp = (bits + 1) / 2;
123    bitsq = bits - bitsp;
124
125    /* We need the RSA components non-NULL */
126    if (!rsa->n && ((rsa->n = BN_new()) == NULL))
127        goto err;
128    if (!rsa->d && ((rsa->d = BN_new()) == NULL))
129        goto err;
130    if (!rsa->e && ((rsa->e = BN_new()) == NULL))
131        goto err;
132    if (!rsa->p && ((rsa->p = BN_new()) == NULL))
133        goto err;
134    if (!rsa->q && ((rsa->q = BN_new()) == NULL))
135        goto err;
136    if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL))
137        goto err;
138    if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL))
139        goto err;
140    if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL))
141        goto err;
142
143    BN_copy(rsa->e, e_value);
144
145    /* generate p and q */
146    for (;;) {
147        if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
148            goto err;
149        if (!BN_sub(r2, rsa->p, BN_value_one()))
150            goto err;
151        if (!BN_gcd(r1, r2, rsa->e, ctx))
152            goto err;
153        if (BN_is_one(r1))
154            break;
155        if (!BN_GENCB_call(cb, 2, n++))
156            goto err;
157    }
158    if (!BN_GENCB_call(cb, 3, 0))
159        goto err;
160    for (;;) {
161        /*
162         * When generating ridiculously small keys, we can get stuck
163         * continually regenerating the same prime values. Check for this and
164         * bail if it happens 3 times.
165         */
166        unsigned int degenerate = 0;
167        do {
168            if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
169                goto err;
170        } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
171        if (degenerate == 3) {
172            ok = 0;             /* we set our own err */
173            RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
174            goto err;
175        }
176        if (!BN_sub(r2, rsa->q, BN_value_one()))
177            goto err;
178        if (!BN_gcd(r1, r2, rsa->e, ctx))
179            goto err;
180        if (BN_is_one(r1))
181            break;
182        if (!BN_GENCB_call(cb, 2, n++))
183            goto err;
184    }
185    if (!BN_GENCB_call(cb, 3, 1))
186        goto err;
187    if (BN_cmp(rsa->p, rsa->q) < 0) {
188        tmp = rsa->p;
189        rsa->p = rsa->q;
190        rsa->q = tmp;
191    }
192
193    /* calculate n */
194    if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))
195        goto err;
196
197    /* calculate d */
198    if (!BN_sub(r1, rsa->p, BN_value_one()))
199        goto err;               /* p-1 */
200    if (!BN_sub(r2, rsa->q, BN_value_one()))
201        goto err;               /* q-1 */
202    if (!BN_mul(r0, r1, r2, ctx))
203        goto err;               /* (p-1)(q-1) */
204    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
205        pr0 = &local_r0;
206        BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
207    } else
208        pr0 = r0;
209    if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx))
210        goto err;               /* d */
211
212    /* set up d for correct BN_FLG_CONSTTIME flag */
213    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
214        d = &local_d;
215        BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
216    } else
217        d = rsa->d;
218
219    /* calculate d mod (p-1) */
220    if (!BN_mod(rsa->dmp1, d, r1, ctx))
221        goto err;
222
223    /* calculate d mod (q-1) */
224    if (!BN_mod(rsa->dmq1, d, r2, ctx))
225        goto err;
226
227    /* calculate inverse of q mod p */
228    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
229        p = &local_p;
230        BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
231    } else
232        p = rsa->p;
233    if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx))
234        goto err;
235
236    ok = 1;
237 err:
238    if (ok == -1) {
239        RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
240        ok = 0;
241    }
242    if (ctx != NULL) {
243        BN_CTX_end(ctx);
244        BN_CTX_free(ctx);
245    }
246
247    return ok;
248}
249